George Willis Ritchey

George Willis Ritchey (born December 31, 1864 in Tupper's Plains, Ohio , † November 4, 1945 ) was an American optician , telescope builder and astronomer .

life and work

Ritchey came from a family of artisans who had been carpentry and furniture for three generations , and who took pride in their excellent products.

From 1880 to 1882 he studied engineering at the University of Cincinnati . During this time he developed an interest in astronomy and worked intermittently at the university's observatory . His focus was more on practical applications, such as telescope technology, than theoretical astronomy. He dealt intensively with the manufacture of optical lenses and mirrors .

The refraction of light in lenses, which depends on the color of the light , leads to image errors in telescopes . This fundamental difficulty led Ritchey to deal with the optimization of reflector telescopes . He was an excellent craftsman and improved the methods of mirroring glass surfaces and constructed parabolic secondary mirrors , which reduced the shadowing .

In 1890, while Ritchey was employed by the Chicago Maunal Training School, he met George Ellery Hale , an astrophysicist and director of his own observatory, the Kenwood Physical Observatory. The two worked together from then on, with Ritchey preparing photographic plates for Hale and, in return, allowed to use his instruments. Ritchey optimized the methods of photography of stars and misty objects.

In 1892, Hale was a candidate for the post of director of a planned observatory at the University of Chicago . Ritchey took a job at the university, doing optics, and making lenses and mirrors. During this time he was working on a reflector with a 24 inch (60 cm) primary mirror. The telescope was later used at the Yerkes Observatory . In 1896, Hale commissioned Ritchey to negotiate and prepare for the construction of a 60-inch (1.54 m) reflector at the Yerkes Observatory. It took Ritchey a decade to prepare for the glass mirror. The instrument was eventually installed at the Mount Wilson Observatory in California .

In 1897 Ritchey took over the supervision of the manufacture of a refractor with a 40-inch (1 m) lens, the main instrument of the Yerkes Observatory, with numerous mechanical and optical problems to solve. This cemented his reputation as an excellent optician and telescope builder.

In the following years he constructed several telescopes, including a “horizontal telescope” consisting of a coelostat with 24 and 30 inch mirrors, made numerous improvements to the 40 inch refractor and optimized astrophotography .

Ritchey's background and successes were closely linked to Hale. When he moved to Mount Wilson Observatory in 1905, Ritchey went with him. Hale intended to build a giant telescope with a 100-inch (2.54 m) mirror diameter, and Ritchey realized this bold idea. In 1919, however, it came to a break - Ritchey's fame increasingly aroused the envy of the jealous Hale. Ritchey dropped out before Hale could fire him, and worked as a lime and orange farmer. However, this company deprived him of all savings.

Because of his excellent reputation, Ritchey was invited to France , where he lived for a total of seven years. Here he developed the Ritchey-Chrétien-Cassegrain telescope with Henri Chrétien .

In 1930 he returned to the USA and received an order from the United States Naval Observatory to manufacture a telescope. Due to his age and decreasing physical strength, he damaged a mirror that he was working on. Although the mirror showed only minor cracks, the United States Navy lost confidence in its capabilities and withdrew the contract.

Ritchey retired to his farm, where he studied astronomy until his death in 1945.

Awards and honors

• 1924 Jules Janssen Prize
• 1935 naming of the lunar crater Ritchey
• 1973 Naming of the Martian crater Ritchey

Web links

• Publications by GW Ritchey in the Astrophysics Data System

• FJ Hargreaves: George Willis Ritchey. Monthly Notices of the Royal Astronomical Society, Vol. 107 (1947), pp. 36–38 (obituary, English)

• Comparison of today's technology with Ritchey's possibilities